The present invention relates to automated data storage libraries for storing and retrieving cartridges with data storage media therein, for use by data processing apparatus having access to such libraries.
Automated data storage libraries provide a data storage environment in which large quantities of data are distributed between a plurality of discrete data storage elements, such as magnetic tape or optical disk cartridges, which are placed in addressable storage cell locations arranged in one or more storage cell banks. The storage elements are accessed using positionable cartridge picker mechanisms which may include one or more selectively activatable cartridge grippers.
In order to transport a data storage element between storage cell locations, one of which may contain a data read/write unit in communication with a host data processing system, a picker mechanism is first positioned at a source storage cell containing a data storage element to be retrieved. A gripper is activated to engage the storage element and retract it from the storage cell. The picker mechanism is then positioned at a destination cell and the gripper is again activated to insert the storage element in the storage cell and release it.
Data storage libraries have been proposed in which pickers are used to access columns of cartridge magazines from either side. That arrangement has the capability to provide high performance provided the cartridge magazine columns are arranged in rows on either side of each picker. In addition, a transverse mechanism must be added to allow the picker to serve more than one column of cartridge magazines. Transverse mechanisms are typically slow and in some cases unreliable. To maximize cost effectiveness, the transverse mechanism must span more than two cartridge magazine columns. Consequently, performance is compromised.
Accordingly, an evident need exists for an automated data storage library having multiple gripper picker capability but without the attendant disadvantages of transverse mechanisms. What is required is a system of reduced complexity and cost in which data storage and retrieval times are effectively minimized.